Yes, you can. But it will require a long process from code end. And right now we do not have to build the dev docs. We are in the process of it. But you can take the help of Prestashop Dev Docs as QloApps is made on Prestashop.

As I mentioned earlier also that for those fields whose translation does not exist by default system show those fields in default language rather than showing them blank. And the only way around is to translate those fields manually.

@duongledong4 At the front-end the option to choose language appears in the footer block. https://prnt.sc/lbudlp But it will only appear if you have installed two or more languages. If only one language is installed on your website then the option will not appear as then there is no use of it.